Invasive Cardiopulmonary Exercise Testing in Chronic Thromboembolic Pulmonary Disease; Obesity and the VE/VCO2 Relationship

• Published in: Journal of clinical medicine 2024-12, Vol.13 (24), p.7702
• Main Authors: Oliveros, Estefania, Mauri, Madeline, Pietrowicz, Rylie, Sadek, Ahmed, Lakhter, Vladimir, Bashir, Riyaz, Auger, William R., Vaidya, Anjali, Forfia, Paul R.
• Format: Article
• Language: English
• Subjects: Body mass index; Dyspnea; Hemodynamics; Medical imaging; Metabolism; Missing data; Obesity; Pulmonary arteries; Pulmonary embolisms; Pulmonary hypertension; Thromboembolism; Veins & arteries; Ventilation
• ISSN: 2077-0383; 2077-0383
• DOI: 10.3390/jcm13247702

Background: Invasive cardiopulmonary exercise testing (iCPET) provides valuable insight into dyspnea in patients with chronic thromboembolic pulmonary disease, in part through an increased relationship of minute ventilation to CO2 production (VE/VCO2). Obesity lowers the VE/VCO2 in patients without cardiopulmonary disease; however, whether this holds true in obese subjects with chronic thromboembolic pulmonary hypertension (CTEPH) and chronic thromboembolic pulmonary disease (CTEPD) is unknown. Objective: Report on the iCPET findings of patients with CTEPH and CTEPD and investigate the relationship between obesity and gas exchange parameters, especially VE/VCO2 in these patients. Methods: Retrospective analysis of CTEPH and CTEPD patients undergoing iCPET. Results: We studied 60 patients; 34 (56.7%) had CTEPH and 26 (43.3%) had CTEPD. The mean age was 61.2 ± 14 years and the mean BMI was 31.8 ± 8.3 mg/kg2. A higher VE/VCO2 (41.9 ± 10.2 vs. 36.8 ± 8.9; p = 0.045) was observed in CTEPH vs. CTEPD. There was an inverse relationship between the VE/VCO2 slope and BMI. For an increase of 1 point in BMI, the VE/VCO2 slope fell by 0.6 in CTEPD and 0.35 in CTEPH (p < 0.001). The mean VE/VCO2 slope in CTEPH and CTEPD groups was 48.6 ± 10.4 in BMI < 25 and 31.3 ± 6.5 in BMI > 35 (p < 0.001). The lower VE/VCO2 slope in obesity relates to an increased VCO2/work rate relationship; there was no difference in the VE/work relationship. Conclusions: The VE/VCO2 slope is markedly reduced by obesity, independent of the level of pulmonary vascular obstruction in CTEPH or CTEPD. Thus, obesity masks key physiologic evidence of pulmonary vascular obstruction on the gas exchange assessment of obese individuals.